1. Field of the Invention
The invention relates to on-line optical monitoring within a gas turbine combustor section, and more particularly to an optical system and inspection method that mounts one or more optical cameras outside a combustor man way service access on a man way cover having an optical window. The external camera field of view is oriented through the optical window and captures images of combustion section internal components, such as transitions. Image information is used to inspect, monitor and/or map one or more of observable structural condition, vibration and/or temperature distributions within the combustor section.
2. Description of the Prior Art
Monitoring of steady state and transient temperature and/or vibration characteristics within a gas turbine combustor section, and especially the transition components, are desirable tools for turbine design, validation and operation. Those components are susceptible to induced temperature and vibration transient excitations caused by combustion gas dynamics. Given the efficiency and emissions criteria, the operation of gas turbines requires a balancing of design and operational approaches to maintain efficiency, meet emission standards, and avoid vibrational and/or thermal damage due to undesired combustion dynamics characteristics. Thus during gas turbine engine design and subsequent field operation it is beneficial to monitor either or both of combustion thermal and vibration characteristics, whether transient or steady-state, that may damage combustor components such as transitions.
In particular, on-line vibration and thermal monitoring of combustor transitions with instruments is difficult given the local pressure and temperature conditions within a combustor. Known combustion characteristic monitoring instrumentation include single thermocouples or thermocouple arrays oriented within the combustor, that associate temperature and/or changes in temperature with combustion characteristics. However, even an array of thermocouples only provides localized temperature information at discrete locations that may not necessarily be extrapolated to determine temperature conditions in other combustor locations that do not have thermocouples. On-line monitoring instruments embedded within the combustor section are subject to greater temperature and pressure environments than ambient conditions outside the combustor section. Embedded instruments are susceptible to damage from hot pressurized combustion gasses, reducing their potential service reliability, and lifetime. Failed embedded instruments require engine shutdown—hence service interruption—to facilitate their removal or replacement.
Other known gas turbine combustor section temperature and vibration monitoring instrumentation determine local characteristics at monitored sites. However, as with thermocouple arrays, the localized information obtained at discrete locations that may not necessarily be extrapolated to determine similar information in other combustor locations. Exemplary known localized temperature and vibration monitoring instrumentation sensors include: embedded pressure transducers (e.g., piezo-electric transducers); embedded and externally mounted accelerometers; and optical systems that associate flame luminescence with combustion thermoacoustic vibration characteristics. The previously cited commonly owned co-pending United States patent application entitled “System For Remote Vibration Detection On Combustor Basket And Transition In Gas Turbines”, filed Aug. 22, 2012 and assigned Ser. No. 13/591,635 is directed to externally mounted photonic transmitters and receivers that reflect photons off combustor section internal surfaces and correlate the reflections with internal vibration characteristics. The externally mounted transmitters and receivers pass photons through optical windows affixed to inspection ports and the like. Other laser-optical sensors employing backscatter, diffraction or phase-Doppler principles have been proposed for monitoring cooling water injection content and droplet distribution within the combustor.
Thus, a need exists for an on-line gas turbine combustor section optical image monitoring system that is capable of inspecting, monitoring and/or mapping one or more of visual images, vibration and/or temperature distributions within the combustor section, such as along the length of a combustor transition.
Another need exists for an on-line gas turbine combustor section optical image monitoring system that is externally mounted to a gas turbine combustor without altering the housing structure.
Another need exists for an on-line gas turbine combustor section optical image monitoring system that scans and gathers image information along a substantial length of the combustor section from a single viewing location.